The present invention relates to an automatic music or song selecting device. More particularly, the invention relates to improvements in an automatic music or song selecting device for automatically selecting any arbitrary music or song of two or more recorded on one side surface of a recording disc.
In such a conventional automatic music or song selecting device, a pickup cartridge incorporates an intermusic or intersong sensor having a light source and a photodetector and which is mounted in the vicinity of the tip of the stylus of the cartridge. When the pickup cartridge thus constructed is moved along the surface of the recording disc together with the intermusic sensor, light emitted from the light source and reflected by the surface of the recording disc is detected by the photodetector. The intermusic or intersong sensor of the photodetector thus detects the space or interval between adjacent music or songs on the recording disc on the basis of variations in the light reflected from the recording disc and accordingly produces an output signal varying in magnitude in accordance with the variations of the light reflected from the recording disc.
When the counted number of spaces between the adjacent songs on the recording disc coincides with the number of songs designated externally, the movement of the pickup cartridge arm is suspended. The pickup cartridge is thereafter lowered onto the recording disc and the song thus designated will be subsequently reproduced on the recording disc.
The arm however tends to move past the position where it is stopped due to the momemtum of the arm and to characteristics of the drive unit for the arm. To compensate for this, a certain conventional automatic music selecting device has been constructed in which the arm is over a short distance in a reverse direction upon suspension of the movement of the arm so as to reduce the error in the positioning of the cartridge.
Since the recording disc is rotating when the intermusic sensor detects intermediate spaces between adjacent songs on the recording disc as described above in any of the prior automatic music selecting devices, the tip of the stylus of the pickup cartridge disposed at an intermediate position between adjacent songs at the time of detecting the intermediate space therebetween will not be correctly located at the intermediate space between the adjacent songs on the recoding disc but will be longitudinally displaced back and forth when the stylus is actually lowered onto the surface of the recording disc if the disc has an eccentric center, for instance. This is disadvantageous in that the tip of the stylus will then be lowered onto the disc of the last part of the previous song or at the initial part of the desired song so that the music will start from the last part of the previous song or from a point into the desired song to be next reproduced.
More specifically, the conventional automatic music selecting device has a drawback due to eccentricity of the recording disc. If the eccentricity of the disc exceeds the length of the intermediate space between adjacent songs, the pickup cartridge cannot in principle be lowered accurately at the desired intermediate position between adjacent songs on the recording disc.
In order to eliminate the above-described drawbacks of the conventional automatic music selecting device and to provide a device capable of accurately lowering the tip of the stylus onto a disc at a correct intermediate position between the adjacent songs on the recording disc, even if the disc is eccentric, an improved automatic music selecting device has been proposed in which an output signal level from an intermusic sensor is stored when movement of the arm is stopped upon selection of a desired song on the recording disc, the output signal level thus stored is compared with an output signal level obtained thereafter from the same intermusic sensor, and the position of the arm is finely adjusted on the basis of the compared result.
If there is a displacement of the position between the tip of the stylus and the intermusic sensor, even if the position of the arm is finely adjusted as described above so that the position of the intermusic sensor is corrected, the tip of the stylus will still be lowered away from the intermediate position between adjacent songs.
In order to further correct the displacement of the intermusic sensor thus lowered, a mechanical correcting mechanism has been provided at the intermusic sensor so as to finely adjust the position of the tip of the stylus of the cartridge with respect to the intermusic sensor. This correcting mechanism further exhibits other disadvantages and drawbacks in that a complicated mechanical structure must be provided at the cartridge and adjustment of the stylus must be made at the end of the cartridge. Such an adjustment is intricate and requires a large number of steps.
Accordingly, a primary object of the invention is to provide an automatic music selecting device in which a pickup cartridge can be accurately lowered onto a disc at an intermediate position between adjacent songs on the disc, even if the disc is eccentric.
The nature, principle and utility of the invention will become more apparent from the following description when read in conjunction with the accompanying drawings.